Sulfuric Acid-Catalyzed Dehydration of Sorbitol: Mechanistic Study on Preferential Formation of 1,4-Sorbitan
作者:Mizuho Yabushita、Hirokazu Kobayashi、Abhijit Shrotri、Kenji Hara、Shogo Ito、Atsushi Fukuoka
DOI:10.1246/bcsj.20150080
日期:2015.7.15
1,4-Sorbitan is a precursor to environmentally benign surfactants, which can be produced from biomass via sorbitol. Currently, sulfuric acid-catalyzed dehydration of sorbitol is the most widely used route for industrial synthesis of 1,4-sorbitan. In this work, we have studied the mechanism of the sorbitol dehydration by sulfuric acid. Our results show that both thermodynamic and kinetic parameters play significant roles to determine the yield of 1,4-sorbitan. Sorbitol preferentially forms an adduct with sulfuric acid, thereby inhibiting the subsequent dehydration of 1,4-sorbitan to isosorbide. Furthermore, a reaction mechanism is proposed for the dehydration reaction, which involves an SN2 reaction on primary C1 of sorbitol attacked by OH of secondary C4.
1,4-山梨醇是一种环保型表面活性剂的前体,可通过山梨醇从生物质中生产。目前,硫酸催化山梨醇脱水是工业合成 1,4-山梨醇酐最广泛使用的途径。在这项工作中,我们研究了硫酸催化山梨醇脱水的机理。研究结果表明,热力学和动力学参数对 1,4-山梨糖醇的产率起着重要作用。山梨醇优先与硫酸形成加合物,从而抑制了 1,4-山梨醇随后脱水生成异山梨醇苷。此外,还提出了脱水反应的反应机理,即山梨醇的一级 C1 受二级 C4 的羟基攻击而发生 SN2 反应。